Brush holder



Dec. 23, 1930. p W, BAKER 1,785,996

BRUSH HOLDER Filed Jan. 26, 1929 In ntor uw KER By Att'y.

Patented Dec. 23, 1930 UNITED STATES PATENT OFFICE PAUL W. BAKER, OF ST.LOUIS, MISSOURI, ASSIGNOR TO WAGNER `EIiEC'IIEtIC CORPORA- TION, OF ST.LOUIS, MISSOURI, A CORPORATION OF DELAWARE BRUSH HOLDER I Applicationfiled January 26, 1929.

My invention relates to a brush holder and associated means foractuating the brushes carried thereby. Nhile it is applicable tomachines having any form of commutator,

it is particularly advantageous for use in machines having a commutatorWhose contact surface is at right angles to the axis of the rotor.

In motors for certain kinds of service, such as operating refrigeratingdevices and other apparatus in the household, it is highly desirablethat no noise of any kind be produced during the starting and stoppingof the machine, nor during normal operation, and -one source of noise inprior machines has been the chattering of the brushes due to thevibration of the brushes against the walls of the brush holder slots,which vibration is produced by the irregularities of the commutatorsurface, and in machines having a vertical face commutator the slightlongitudinal reciproca-tions of the rotor cause added brush motion.Inequality of brush pressure on the commutator is also a source ofnoise.

One of the objects of my invention is to overcome brush noise due tochatteringf and another object is to provide means for applying andmaintaining equal pressure on the brushes. Also, my invention has theadvantage of reducing the number of brush advancing springs which haveheretofore been employed.

In the accompanying drawings, Figure 1 is a top plan view of a brushholder and associated parts embodying my invention; Figure 2 shows across section of the holder along the line 2-2 of Figure 1, and inaddition thereto its relation to the commutator and other parts of aWell known type of single phase motor having a vertical face commutatorand provided With centrifugal means for moving the brushes out ofcontact with the commutator after the motor has been started; and Figure3 diagrammatically illustrates a side vieW of a pair of brushes andguides therefor, and illustrates brush advancing means and its relationto the brushes whereby the objects of my invention are secured.

Serial No. 335,165.

The' brush holder comprises a casting 1 having radially extending arms2, which are provided With brush guides formed by longitudinal slots 1nthe arms and slot closing plates 3and, as to the features just menftioned, isV constructed in the manner described in Evans Patent No.1,354,899 issued October A5, 1920.

rEhe holder illustrated in Figure 1 is for a machine requiring two pairsof brushes and' is provided with integral studs 4; centrally positionedbetween the guides for the brushes of each pair. Springs 5 Vcoiled atthe center are'mounted on these studs and have one end of the Wire fromWhich they are formed eX tended to bear upon a brush at one Side of thestud and the other end extended to bear 'upon the brush at the otherside of the stud.

brushes I apply the brush advancing pressure at an angle to t-hedirection of advance, as in dicated by the arrows in Figure 3, andthereby hold the brush in pressure engagement with a part or parts ofthe Walls of the brush guide and thus' prevent lateral brush vibrationand the consequent noise usually referred to as chattering rlhemechanism shown in Figure 2 for mounting and actuating the brush holderbeing of Well known construction need not be more than generallydescribed. The holder is mounted on a circular extension 6 of the endYplate l of thermotor. The holder is actuated into operative relationWith the commutator 8 by means of the spring 9 on the motor shaft 10,and is moved out of operative relation by means of collar 11 actuated bythe rods 12 Which are connected to the centrifugal mechanism (notshoWn).In the running position the commutator is short-cirdio cuited by a.plurality of short-circuiting` plates 14 carried by the collar 11.

As shown in Figures 1 and 2, the walls of the brush guides are providedwith slots 13 whereby the brush advancing spring ends may continue tobear on the brushes until they are shortened by wear to a predetermineddegree.

In a particular motor certain brush preseures cause less noise thanothers and it is desirable to select the pressure producing the least.Means for equalization of brush pressure has the advantage thatadjustment of one spring establishes the desired pressure on two brushesand maintains it. n

It will be apparent that my invention has the advantage of convenientlyand cheaply securing' equality of brush pressures and elimination ofbrush chattering.

Having fully described my invention, what I Vclaim as new and desire tosecure by Letters Patent of the United States is 1. In a dynamo electricmachine, the combination with a brush holder provided with brush guideslots and brushes therein. of a resilient brush follow-er having one endbearing on one of a pair of brushes and the other end bearing on theother brush, and a pivot support for -said follower intermediate itsends whereby the pressure on one brush will be proportional to thepressure on the other brush.

2. The combination of a brush holder for dynamo electric machines havingertending` arms provided with brush guide slots and having a studprojecting between said arms, brushes in said slots, and a brushfollower of spring,r material coiled intermediate its ends and havingone end bearing upon one brush and the other bearing upon the otherbrush, said coil portion being pivotally mounted 0n said stud.

3. In a dynamo electric machine, a brush holder comprising a hub havingtwo radially extending` arms provided with brush carrying slots andhaving a radially extending` stud centrally positioned between the arms,brushes in said slots, a resilient member pivoted on the stud andhaving` one of its ends arranged to apply advancing pressure to thebrush on one side of the stud and its other end to apply advancing`pressure to the brush on the opposite vside of the stud, whereby a.substantially equal pressure will be applied to each brush.

l. In a dynamo electric machine, the combination of two commutatorbrushes, means forming guides therefor, a pivot, a resilient memberrotatably mounted on said pivot and having one of its ends arranged toapply advancing pressure to one brush and the other end to applyadvancing; pressure to the other brush, each end being` also adapted toapply its pressure to its brush in such direction as to tend to maintainthe brush in lateral contact with its guide, the pivot of the resilientmember being also so located that the total pressures applied by it toeach b-rush will be equal.

In testimony whereof, I hereunto a'liix my signature, this 22nd day ofJanuary, 1929. PAUL W. BAKER.

